1. Field of the Invention
The invention relates to a valve coupling, and more particularly to a quick disconnect coupling for use with air and hydraulic systems, such as refrigeration and air conditioning systems.
2. Description of the Related Art
Various couplings are used in conjunction with access valves having access cores. An access valve typically has a sealing member, or access core, which is biased into the closed position by a spring. Known couplings generally have a depressor prong of some type which contacts the access core when the coupling is affixed to the access valve, depressing the access core into a position allowing communication through the coupling and into the valve.
Such a device is shown in Olson U.S. Pat. No. 3,840,967. Olson discloses a coupling which is attached to an access valve with a nut that threadably engages the head of the access valve. A depressor can then be manually maneuvered to engage the access core of the access valve, establishing communication through the coupling and to the access valve. Such a device, however, suffers from two distinct disadvantages. The first disadvantage is that the coupling must be attached to the access valve by a threaded nut which does not allow for a rapid attachment of the coupling to the access valve. Second, the coupling can be removed from the access valve while the depressor is still in the position of pushing against the access core of the access valve which allows the potential of leakage when the coupling is disconnected.
Another type of coupling is disclosed in Morse U.S. Pat. No. 3,424,181. Morse discloses a coupling which again is attached to an access valve with a threaded nut. A manually operated depressor can then be maneuvered to contact the access core of the access valve. As mentioned regarding the Olson patent, Morse also suffers from the disadvantages of having to be threaded onto the access valve, and of the possibility of leakage should the nut be removed while the depressor is still in its depressing position.
The problem of manual connection to an access valve is addressed by various inventors. Representative of this approach is Spalink et al U.S. Pat. No. 4,892,117. Spalink discloses a refrigeration coupling which has a slidable sleeve for quick connecting and disconnecting with an access valve. The sliding sleeve is mounted on the end of the coupling and biased by a spring towards the end of the coupling. When the sleeve is pushed by the spring all the way towards the end of the coupling, ball bearings are urged through cavities in the housing of the coupling and project into the passageway on the inside of the housing of the coupling. Access valves are generally designed with a ridge about the outer periphery. The ball bearings are thus forced to lock about this ridge which causes the quick disconnect coupling to hold fast to the access valve until released by pulling back on the sliding sleeve.
Spalink, however, suffers from the disadvantage that the depressing member is spring operated. Thus, the coupling cannot be attached to an access valve without some leakage occurring. When the coupling is pressed down over the access valve in order to lock the sliding sleeve, the depressor contacts the core of the access valve and prematurely establishes communication. Conversely, in highly pressurized systems, the pressure on the depressor member of the quick disconnect coupling could be so great as to blow the coupling back away from the access valve causing possible injury to the operator of the coupling. Also, in such highly pressurized systems, the pressure from the system on the inside of the access core of the access valve may be so great as to prevent the spring operated depressing member from actually establishing communication through the access valve.
Such a coupling as that disclosed in Spalink also suffers from the disadvantage that communication through the access valve cannot be terminated prior to removing the quick disconnect coupling. Thus, as in the other art, removal of the coupling from the access valve will result in leakage of the gas in the pressurized system to the atmosphere.
It is thus an object of the invention to provide a quick disconnect coupling which can be attached to an access valve in a quick and efficient manner prior to establishing communication through the valve.
It is a further object of the invention to provide a quick disconnect coupling for use in highly pressurized systems which cannot be disconnected unless the manually operated depressor is withdrawn, sealing the access valve.
It is yet another object of the invention to provide a quick disconnect coupling which seals itself when the manually operated depressor is withdrawn from the access valve so that a hose supplying the quick disconnect coupling remains pressurized.
The result of the above objects is to provide a quick disconnect coupling which virtually eliminates leakage of pressurized gas from a closed system into the atmosphere, and which also provides safer conditions for operators of the quick disconnect coupling.